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hanced design of hourglass truss sandwich structures for compressive resistance 1

2*

2

FENG LiJia , YU GuoCai , MA Li , WU LinZhi

2,3*

& ZHANG AMan

1

1

2

College of Shipbuilding Engineering, Harbin Engineering University, Harbin 150001, China; Key Laboratory of Advanced Ship Materials and Mechanics, College of Aerospace and Civil Engineering, Harbin Engineering University, Harbin 150001, China; 3 Center for Composite Materials, Harbin Institute of Technology, Harbin 150001, China

Received October 15, 2019; accepted March 10, 2020; published online October 27, 2020

In this article, the design of the hourglass truss sandwich structure is improved by optimizing the number of layers to enhance the compressive strength of both the core and the face sheet and then its mechanical performance. The hourglass truss structures characterized by three different numbers of layers are manufactured using an interlocking and vacuum brazing method. The effect of the layer number of the hourglass core panels on their out-of-plane compression and in-plane compression performance is investigated, and the results from calculations and experiments are in reasonable agreement. The results show that as the layer number of the hourglass core increases, the out-of-plane compressive strengths show little change, but their energy absorption properties are effectively increased. The in-plane compressive failure mechanism maps are constructed, and the specimens are designed to examine the local elastic and inelastic buckling failure modes of the face sheets. The results suggest that as the number of layers of the hourglass core increases, its maximum in-plane compressive load increases. The maximum in-plane compressive loads of the two-layer hourglass truss panels are 57%–70% higher than those of the single-layer panels. It can also be concluded that the out-of-plane and in-plane compression mechanical properties of the multilayer hourglass truss outperform those of the pyramidal truss. Furthermore, the number of layers of the hourglass core is optimized in consideration of both mechanical properties and fabrication cost. multilayer, hourglass truss, truss sandwich structure, out-of-plane compression, in-plane compression Citation:

Feng L J, Yu G C, Ma L, et al. Enhanced design of hourglass truss sandwich structures for compressive resistance. Sci China Tech Sci, 2020, 63, https://doi.org/10.1007/s11431-019-1556-8

1 Introduction Cellular lattice truss sandwich structures based on various topologies have attracted significant interest, and their mechanical properties have been extensively studied in refs. [1– 13]. The cell size and mechanical performance of the core together determine the strengths of such structures, wherein the size of the unit cell affects the distance between nodes and then the buckling resistance of the face sheet [14]. Studies show that the mechanical property of the pyramidal truss *

Corresponding authors (email: [email protected]; [email protected])

structure is very competitive with that of existing topolog